PSI - Issue 80

Saverio Giulio Barbieri et al. / Procedia Structural Integrity 80 (2026) 279–288 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 7. Deformed shapes of the tubes: (a) G4852 without creep; (b) HK – 40 without creep; (c) G4852 with creep; (d) HK – 40 with creep.

Table 6. Results of the simulations accounting the central manifold mounting strategy. G4852 HK – 40 Creep excluded Maximum von Mises stress 40.0 MPa 31.1 MPa Creep included Maximum von Mises stress 71.1 MPa 155.7 MPa Maximum equivalent creep strain 3.0 ⋅ 10 -3 2.8 ⋅ 10 -2 Total axial displacement 284 mm 670 mm

5. Conclusions The paper has presented a Finite Element methodology for thermo-structural analysis of tubes in a tubular heat exchanger reactor for synthetic fuel production. Two materials were examined in detail: Centralloy® G4852 Micro and HK – 40, with particular focus on the creep phenomenon. The research progressed through several phases, beginning with a comprehensive evaluation of material properties, followed by an assessment of various mechanical boundary conditions affecting these tubes. The results demonstrated that without considering creep, both materials exhibited nearly identical responses. However, when creep was included in the analysis, G4852 significantly outperformed HK – 40, showing superior resistance to deformation under sustained loading. Further investigation addressed the influence of different support configurations for the catalytic material contained within the tubes. The final phase examined two mounting strategies for connecting tube arrays: individual manifolds for each tube versus a single central manifold. The individual manifold configuration aligned with the calculations performed in the earlier analyses. For the central manifold arrangement, a simplified preliminary design was incorporated into the model. The central manifold configuration substantially increases stress levels when creep is not considered. When creep was included, both configurations appeared quantitatively similar in terms of overall stress and strain values. However, the qualitative deformation patterns differed significantly between the two mounting strategies. Failing to properly account for these deformation patterns during design could compromise the functionality of the entire system. The methodology described and the results obtained have provided valuable insights for the early stages of design when evaluating different materials, boundary conditions, and geometric layouts. This approach may help engineers to make informed decisions regarding material selection, structural configuration, and operational parameters to optimize the performance and longevity of tubular heat exchanger reactors in synthetic fuel production systems.